1. Field of the Invention
This invention relates to an industrial robot arm secured to a base frame and receiving a driving force to be moved, and a method of producing this arm.
2. Description of the Prior Art
In general, industrial robot arms are each constructed such that a rotary shaft, a bearing and the like are welded to an arm outer plate formed into predetermined dimensions by bending, welding or the like, and reinforcing plates are secured thereto if necessary.
In order to accurately carry out the works of welding, assembling and the like by means of a mechanical hand provided at the forward end portion of this robot arm, it is necessary to hold with high accuracy the relative dimensions among the rotary shaft, the bearing, etc. secured to the arm outer plate.
Heretofore, upon correction of distortions due to welding in the robot arm after the production, a reference surface has been provided on a predetermined position of this robot arm by the grinding or the like, whereby the grinding of the outer diameters of the rotary shafts and the hole forming in the bearings are carried out.
As a result, many complicated stages of work have been required for producing the robot arm with high accuracy.